BERLIN — Faced with a plummeting population, rising labor shortages and widespread emigration, Prime Minister Viktor Orban of Hungary has long taken an unconventional approach to increasing the size and productivity of Hungary’s work force.

He offered university scholarships only to those who promised to stay in Hungary. He gave citizenship to ethnic Hungarians living beyond the borders. And late last year, he increased the amount of overtime employers can demand of workers — to 400 hours a year.

But on Sunday, Mr. Orban announced one of his most ambitious plans yet: Any Hungarian woman with four or more children will no longer pay income tax.

Anything to avoid immigration.

“We are living in times when fewer and fewer children are being born throughout Europe. People in the West are responding to this with immigration,” Mr. Orban said in a speech on Sunday. “Hungarians see this in a different light. We do not need numbers, but Hungarian children.”

No country in the European Union has a fertility rate high enough to replenish its population without immigration — but Hungary, with about 1.5 children per woman, is among the most sluggish. It also is among the most reluctant to accept foreign workers to help plug the gaps.

Even in the Czech Republic and Poland, where anti-immigrant sentiment also runs high, governments are planning to admit, or have already admitted, workers from across Asia.

But Mr. Orban, a far-right leader, has said he does not want the color of Hungarians to be “mixed with those of others.” He led European opposition to refugees during the 2015 migration crisis and has boxed himself into a rhetorical corner that now makes it difficult to change direction.

“Hungary is facing similar structural challenges as other neighbors,” said Milan Nič, an expert on central and Eastern Europe at the German Council on Foreign Relations. “But in Hungary, the government’s policy choices are more limited by its nationalist ideology.”

Instead of encouraging immigration, Mr. Orban said on Sunday that in addition to eliminating taxes for mothers with four or more children, he would reduce mortgage and car payments for parents; introduce new loans for families; allow grandparents to share maternity leave; and increase day care places.

The measures constitute “a regulation of women’s bodies,” said Andrea Peto, a gender studies professor at the Central European University, a college in Budapest. “Their bodies are being used as a resource for national development.”

But some of the measures might lessen Hungary’s gender inequality since they would make it marginally easier for women to balance “their double role as mothers and members of the work force,” Professor Peto said.

In particular, the construction of 21,000 new kindergarten places could make it easier for more women to go back to work. “This is a good step in the right direction,” Professor Peto said.

Still, demography experts said the measure was unlikely to succeed in its primary goal of growing the native Hungarian population. One of the few programs that historically succeeded in boosting the population took place in Communist-era Romania, a totalitarian dictatorship in which abortions and birth control were banned.

Like Hungary, France introduced financial incentives in 2005, but since then its birthrate has remained at around 1.9 children per woman, said Sarah Harper, a demography professor at Oxford University. And it might even have been lower without the influx of immigrants, whose birthrates are typically higher than native-born residents.

“You have to ask: how much is it down to the financial incentives, and how much is it migration and an ethnically diverse population?” Professor Harper said.

Sweden has managed to keep its birthrate above 1.8 children per woman — but only by making it far easier for women to return to work than in Hungary. Unlike in Hungary, child care in Sweden is free for all. Fathers can take parental leave as well as mothers, and in tandem they receive 55 weeks of leave at near full-pay, more than double that allotted to Hungarian mothers.

“There needs to be a package that enables women to take time off work, to return to work, and to combine work with child care, and to give similar support for fathers as well as mothers,” said Professor Harper. “Otherwise the most likely thing is that they will withdraw from the labor market.”

But in Hungary, where voters are generally more conservative than in Sweden, the measures were nevertheless likely to be a vote-winner in elections for the European Parliament later this year, said Csaba Toth, a political analyst at the Republikon Institute, a research group in Budapest.

“In Western Europe there might be a different interpretation, but in a country like Hungary, Orban’s position will be popular,” Mr. Toth said. “It’s targeting middle-class families.”

A version of this article appears in print on , on Page A6 of the New York edition with the headline: Shunning Immigrants, Orban Offers Tax Break if Hungarians Have More Babies. Order Reprints | Today’s Paper | Subscribe